In an effort to understand the immunoregulatory mechanisms in patients with malignancies, we propose to define the cellular response and the modulatory influence of mononuclear cells in the tumor membrane lymphocyte stimulation assay. In this assay system, plasma membranes are prepared from surgical specimens of renal cell carcinoma and autologous adjunct "normal" kidney. The sucrose gradient plasma membranes are adjusted to antigenic equivalence using HLA as a plasma membrane marker in a (51 Cr) microcytotoxicity inhibition assay. autologous peripheral blood lymphocytes are prepared by nylon wood fractionation and stimulated with normal or kidney tumor plasma membranes. Various conditions such as the dose response, kinetics, and the partial biochemical characterization of the lymphocytes stimulating molecule(s) have been established. We now propose to further dissect the in vitro immune response to determine the primary responding mononuclear cell population. Lymphocytes will be prepared by Ficoll-Hypaque gradients and the T cells fractionated by neuraminidase sheep red blood cell rosettes. Subpopulations of T cells will be isolated with ox red blood cells coated with IgG and pentameric IgM. Once the primary responding cell population has been identified, the modulatory influence of the remaining mononuclear cells including B cells and monocytes will be tested. The differential response of lymphocyte population from the tumor, regional and distant lymph nodes will then be evaluated. Our previous biochemical characterization of the lymphocyte stimulating molecule(s) also provides the opportunity to further investigate the differential response to membrane vs. soluble antigen in the absence of immunologically active Ir gene products. These results will provide the foundation for investigating the influence of adjunctive therapy on the immune response in patients with renal cell carcinoma.